I led with the trailer to this summer thriller, because I think it's scarier than the movie itself - not that I wasn't on the edge of my seat (or tucked into the back of it, clenching Jesus's hand) while watching, but I didn't leave the theater checking around corners for creepy silhouettes. Based on this YouTube short (which I haven't watched yet), Lights Out sets up a story, gives the "rules" of its world, and resolves the conflict in a neat 81 minutes, leaving little lingering fears afterwards.
The basic premise is a presence has attached itself to Sophie, the mother of Rebecca, now grown, and Martin, still young. This presence was a part of Sophie's childhood, messed with Rebecca's, and has now returned to disrupt Martin's. Rebecca, still dealing with the issues that came out of her experience, tries to rescue Martin from having to deal with the same things, but the presence seems to follow them and is inexplicably tied to their mother's mental health.
Lights Out shows its viewers the toll depression can take on a family, the redemption of family ties and motherly sacrifices, and the effects of friendships both strong and unhealthy. When I researched it after watching, I found that there was originally a different ending that wasn't shown in theaters. I personally would have appreciated that ending more, and I think it would have upped the scare factor a bit. I also read that there is a sequel planned, which might delve deeper into the issues raised around depression.